Planetary wave coupling processes in the middle atmosphere (30–90km): A study involving MetO and MFR data

Chshyolkova, T.; Manson, A. H.; Meek, C. E.; Avery, S. K.; Thorsen, Denise; MacDougall, J. W.; Hocking, W. K.; Murayama, Yasuhiro; Igarashi, K.

doi:10.1016/j.jastp.2005.05.011

Cited by 24 publications

(22 citation statements)

References 38 publications

Supporting

Mentioning

Contrasting

Order By: Relevance

“…Such was shown in the model-study by Polvani and Saravanan (2000). This is in agreement with earlier findings by Chshyolkova et al (2007) that indicated lower (compared to other years) PW activity at upper stratospheric and mesospheric heights.…”

Section: November-decembersupporting

confidence: 93%

“…The authors of this paper began their research with medium frequency radars, measuring electron densities or winds (60-90 km), and establishing relationships between planetary waves of the lower stratosphere and associated variabilities in the mesosphere-lower thermosphere (MLT). The studies have become more global with time Manson, 1970, 1975;Labitzke et al, 1987;Manson et al, 2002Manson et al, , 2005Chshyolkova et al, 2005Chshyolkova et al, , 2006Chshyolkova et al, , 2007Chshyolkova et al, , 2008. While ground-based observations continue to have great value due to their high time resolution, especially when networks are available, studies that also include global satellite observations are now of greatest value.…”

Section: Introductionmentioning

confidence: 99%

“…United Kingdom Meteorological Office (MetO) analyses). In particular Chshyolkova et al (2006) demonstrated that the 7 month intervals of middle to high latitude westerly winds, which are associated with the winter polar vortex, provide 1-2 equinoctial months when the global middle atmosphere winds are westerly. Planetary Waves (PW) of 12-16 day period exist in both hemispheres and typically from 20-90 km during these times.…”

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

Regional stratospheric warmings in the Pacific-Western Canada (PWC) sector during winter 2004/2005: implications for temperatures, winds, chemical constituents and the characterization of the Polar vortex

2008

Self Cite

View full text Add to dashboard Cite

Abstract. The vortex during winter 2004/2005 was interesting for several reasons. It has been described as "cold" stratospherically, with relatively strong westerly winds. Losses of ozone until the final warming in March were considerable, and comparable to the cold 1999–2000 winter. There were also modest warming events, indicated by peaks in 10 hPa zonal mean temperatures at high latitudes, near 1 January and 1 February. Events associated with a significant regional stratospheric warming in the Pacific-Western Canada (PWC) sector then began and peaked toward the end of February, providing strong longitudinal variations in dynamical characteristics (Chshyolkova et al., 2007; hereafter C07). The associated disturbed vortex of 25 February was displaced from the pole and either elongated (upper) or split into two cyclonic centres (lower). Observations from Microwave Limb Sounder (MLS) on Aura are used here to study the thermal characteristics of the stratosphere in the Canadian-US (253° E) and Scandinavian-Europe (16° E) sectors. Undisturbed high latitude stratopause (55 km) zonal mean temperatures during the mid-winter (December–February) reached 270 K, warmer than empirical-models such as CIRA-86, suggesting that seasonal polar warming due to dynamical influences affects the high altitude stratosphere as well as the mesosphere. There were also significant stratopause differences between Scandinavia and Canada during the warming events of 1 January and 1 February, with higher temperatures near 275 K at 16° E. During the 25 February "PWC" event a warming occurred at low and middle stratospheric heights (10–30 km: 220 K at 253° E) and the stratopause cooled; while over Scandinavia-Europe the stratosphere below ~30 km was relatively cold at 195 K and the stratopause became even warmer (>295 K) and lower (~45 km). The zonal winds followed the associated temperature gradients so that the vertical and latitudinal gradients of the winds differed strongly between Scandinavia-Europe and Canada-US. The data-archive of Aura-MLS was also used to produce height versus latitude contours of ozone and related constituents, using mixing ratios (r) for ClO, N2O and HCl, for the 16° E and 253° E sectors. The Q-diagnostic was used to display the positions of the cyclonic (polar) vortex, using data from the UK Meteorological Office (MetO) analyses. ClO/HCL maxima/minima occurred on 1 February in both sectors, consistent with loss of ozone by heterogeneous chemistry. Low N2O values at high latitudes indicated that both sectors were inside the polar vortex, Time-difference plots show greater reductions in O3 in the Canadian sector. For the 25 February PWC warming event, O3-rich air from lower latitudes continued to be excluded from Europe, while O3 penetrated to at least 82° N over the Canadian sector. The contours for ClO, N2O and HCl at 16° E are consistent with continued ozone loss within the vortex during the event. Finally the thermal and chemical changes at these 16° E and 253° E sectors are placed into a hemispheric context using polar-cylindrical plots, with the following results. Firstly, the mixing ratios of O3, ClO, HNO3, HCL and the temperatures from Aura-MLS were consistent with consensus views of heterogeneous chemistry. Secondly, and consistent with the polar plots of C07, the vortices and their edges were strongly distorted during the 1 January, 1 and 25 February warming events, with sinusoidal shapes consistent with stationary planetary waves of wave-numbers 1 and 2. Thirdly, the distributions of the chemicals followed the curvatures (cyclonic and anticyclonic) of the vortex edges with O3 losses occurring at the cold cyclonic locations. During February these were over Scandinavia-Western Europe and Central-Eastern Canada. Trajectory analysis was applied to the two February warming events. For the 1 February event, the rotation time for air parcels within the peanut-shaped vortex was 3–4 days; while the O3-rich low latitude air that entered the Pacific-Western Canada sector during the 25 February event, showed no signs of becoming trapped within the highly distorted but still strong remnant of the polar vortex.

show abstract

Section: November-decembersupporting

confidence: 93%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 1 more Smart Citation

Regional stratospheric warmings in the Pacific-Western Canada (PWC) sector during winter 2004/2005: implications for temperatures, winds, chemical constituents and the characterization of the Polar vortex

2008

Self Cite

View full text Add to dashboard Cite

show abstract

“…Enhancements in this circulation lead to "stronger down-welling over the pole, therefore warmer polar temperatures, and a weaker polar vortex" (Shepherd, 2000). The polar vortex is subject to disturbances (the so-called minor warmings) and breakdowns, as revealed most dramatically in Sudden Stratospheric Warmings (SSW) (Chshyolkova et al, 2006;Manson et al, 2002d;Liu and Roble, 2002;Shepherd, 2000). Further, given the effects of the PW and polar vortex structure (during SSW) upon hemispheric (especially middle to high latitudes) ozone distributions (Randel, 1993;Baldwin et al, 2003) and also upon the temperatures and winds, and the propagation of various modes into the middle atmosphere, tidal characteristics (especially for the 12-h tide) may be expected to be affected for several months of any winter which is experiencing breakdowns during the mid-winter or spring.…”

Section: Stratospheric Time Sequences (Cmam and Meto) For The Tromsø mentioning

confidence: 99%

Winter warmings, tides and planetary waves: comparisions between CMAM (with interactive chemistry) and MFR-MetO observations and data

et al. 2006

Self Cite

View full text Add to dashboard Cite

Abstract. Following earlier comparisons using the Canadian Middle Atmosphere Model (CMAM, without interactive chemistry), the dynamical characteristics of the model are assessed with interactive chemistry activated. Timesequences of temperatures and winds at Tromsø (70 • N) show that the model has more frequent and earlier stratospheric winter warmings than typically observed. Wavelets at mesospheric heights (76, 85 km) and from equator to polar regions show that CMAM tides are generally larger, but planetary waves (PW) smaller, than medium frequency (MF) radar-derived values.Tides modelled for eight geographic locations during the four seasons are not strikingly different from the earlier CMAM experiment; although monthly data now allow these detailed seasonal variations (local combinations of migrating and non-migrating components) within the mesosphere (circa 50-80 km) to be demonstrated for the first time. The dominant semi-diurnal tide of middle latitudes is, as in the earlier papers, quite well realized in CMAM. Regarding the diurnal tide, it is shown here and in an earlier study by one of the authors, that the main characteristics of the diurnal tide at low latitudes (where the S (1,1) mode dominates) are well captured by the model. However, in this experiment there are some other unobserved features for the diurnal tide, which are quite similar to those noted in the earlier CMAM experiment: low latitude amplitudes are larger than observed Finally, the seasonal variations of planetary wave (PW) activity available from CMAM and the MFR show quite good agreement, apart from the amplitude differences (smaller in CMAM above 70 km). A major difference for the 16-d PW is that CMAM shows large amplitudes before the winter solstice; and for the 2-d PW, while both CMAM and MFR show summer and winter activity, the observed summer mesopause and winter mesospheric wave activities are stronger and more extended in height.Models such as CMAM, operated without dataassimilation, are now able to provide increasingly realistic climatologies of middle atmosphere tides and PW activity. Differences do exist however, and so discussion of the various factors affecting tidal and PW characteristics in atmospheres, modelled and observed, is provided. Other diagnostics of model-characteristics and of future desirable model experiments are suggested.

show abstract

“…Here the SDT data are derived using medium frequency radars (MFR) Chshyolkova et al (2007) and Manson et al (2009). In this study, the radar data are usually analysed at 6 height levels centered on 82, 85, 88, 91, 94 and 97 km.…”

Section: Introductionmentioning

confidence: 99%

Relationship between variability of the semidiurnal tide in the Northern Hemisphere mesosphere and quasi-stationary planetary waves throughout the global middle atmosphere

et al. 2009

Self Cite

View full text Add to dashboard Cite

Abstract. To investigate possible couplings between planetary waves and the semidiurnal tide (SDT), this work examines the statistical correlations between the SDT amplitudes observed in the Northern Hemisphere (NH) mesosphere and stationary planetary wave (SPW) with wavenumber S=1 (SPW1) amplitudes throughout the global stratosphere and mesosphere. The latter are derived from the Aura-MLS temperature measurements. During NH summerfall (July-October), the mesospheric SDT amplitudes observed at Svalbard (78 • N) and Eureka (80 • N) usually do not show persistent correlations with the SPW1 amplitudes in the opposite hemisphere. Although the SDT amplitudes observed at lower latitudes (∼50-70 • N), especially at Saskatoon (52 • N), are often shown to be highly and positively correlated with the SPW1 amplitudes in high southern latitudes, these correlations cannot be sufficiently explained as evidence for a direct physical link between the Southern Hemisphere (SH) winter-early spring SPW and NH summer-early fall mesospheric SDT. This is because the migrating tide's contribution is usually dominant in the mid-high latitude (∼50-70 • N) NH mesosphere during the local late summerearly fall (July-September). The numerical correlation is dominated by similar low-frequency variability or trends between the amplitudes of the NH SDT and SH SPW1 during the respective equinoctial transitions. In contradistinction,Correspondence to: X. Xu (xix303@mail.usask.ca) during NH winter (November-February), the mesospheric SDT amplitudes at northern mid-high latitudes (∼50-80 • N) are observed to be significantly and positively correlated with the SPW1 amplitudes in the same hemisphere in most cases. Because both the SPW and migrating SDT are large in the NH during the local winter, a non-linear interaction between SPW and migrating SDT probably occurs, thus providing a global non-migrating SDT. This is consistent with observations of SDT in Antarctica that are large in summer than in winter. It is suggested that climatological hemispheric asymmetry, e.g. the SH and NH winter characteristics are substantially different, lead to differences in the inter-hemispheric SPW-tide physical links.

show abstract

Planetary wave coupling processes in the middle atmosphere (30–90km): A study involving MetO and MFR data

Cited by 24 publications

References 38 publications

Regional stratospheric warmings in the Pacific-Western Canada (PWC) sector during winter 2004/2005: implications for temperatures, winds, chemical constituents and the characterization of the Polar vortex

Regional stratospheric warmings in the Pacific-Western Canada (PWC) sector during winter 2004/2005: implications for temperatures, winds, chemical constituents and the characterization of the Polar vortex

Winter warmings, tides and planetary waves: comparisions between CMAM (with interactive chemistry) and MFR-MetO observations and data

Relationship between variability of the semidiurnal tide in the Northern Hemisphere mesosphere and quasi-stationary planetary waves throughout the global middle atmosphere

Contact Info

Product

Resources

About